ELECTROSTATIC DISCHARGE PROTECTION OF A CLAMP
The present invention provides an ESD protection circuit for a ESD clamp such as an SCR in the protection of an integrated circuit. In one embodiment of the invention, the SCR having at least one interspersed high-doped first region formed within a first lightly doped region and at least one interspersed high-doped second region formed within a second lightly doped region. The circuit further comprising at least one guardring connected to at least one trigger tap of the SCR to collect the ESD current to provide for a fast and easier triggering of the SCR.
1 . An electrostatic discharge (ESD) protection circuit comprising:
a SCR having at least one interspersed high-doped first region formed within a first lightly doped region and at least one interspersed high-doped second region formed within a second lightly doped region, said SCR coupled between a first voltage potential and a second voltage potential; and
at least one guardring coupled to at least one trigger tap of the SCR.
2 . The ESD protection circuit of claim 1 wherein said guardring comprise the well tap of at least one of a resistor, a capacitor, a diode, a MOS, a SCR and an active source pump.
3 . The ESD protection circuit of claim 1 further comprising at least one series pn junction diode having an anode and a cathode respectively coupled in the forward direction from at least one trigger tap of the SCR to the second voltage potential.
4 . The ESD protection circuit of claim 3 wherein the guardring surrounds at least one of the at least one series pn junction diodes.
5 . The ESD protection circuit of claim 1 wherein the first voltage potential is at least one of an input, output and input/output pad.
6 . The ESD protection circuit of claim 5 wherein the second voltage potential is the ground.
7 . The ESD protection circuit of claim 6 further comprising a third voltage potential, wherein said third voltage potential is a power supply.
8 . The ESD protection circuit of claim 7 further comprising a pn junction diode coupled between the first voltage potential and the third voltage potential.
9 . The ESD protection circuit of claim 8 wherein the at least one guardring surrounds the said pn junction diode.
10 . The ESD protection circuit of claim 1 wherein the first voltage potential is an power supply and the second voltage potential is the ground.
11 . The ESD protection circuit of claim 10 further comprising a third voltage potential, wherein said third voltage potential is at least one of an input, output and input/output pad.
12 . The ESD protection circuit of claim 11 further comprising a pn junction diode coupled between the third voltage potential and the first voltage potential.
13 . The ESD protection circuit of claim 11 wherein said at least one guardring surrounds the pn junction diode.
14 . The ESD protection circuit of claim 1 further comprising a first MOS coupled between the at least one guardring and the trigger tap of the SCR.
15 . The ESD protection circuit of claim 14 further comprising a second MOS coupled between the at least one guardring and one of said first and second voltage potential, wherein said one of the first and second voltage potential is ground.
16 . The ESD protection circuit of claim 15 wherein the first MOS is a NMOS and the second MOS is a PMOS and the gate of the first and the second NMOS are coupled to a power supply.
17 . An integrated circuit having a substrate comprising:
a SCR formed over the said substrate, said SCR having at least one interspersed high-doped first region formed within a first lightly doped region and at least one interspersed high-doped second region formed within a second lightly doped region; and
a pn junction diode directly connected to said SCR without a guardring between the SCR and pn junction.
18 . The circuit of claim 17 wherein a gate is formed between the at least one interspersed high doped region of the diode and the substrate.
19 . The circuit of claim 18 further comprising a control circuit connected to said gate.
20 . The circuit of claim 19 wherein said control circuit is coupled between a first voltage potential and a second voltage potential.
21 . The circuit of claim 19 wherein said control circuit comprises at least one of a RC circuit, voltage detection circuit, current detection circuit, short circuit and open circuit.
22 . The circuit of claim 17 wherein a gate is formed between the at least one interspersed high doped region of the diode and at least one trigger tap of the SCR.
23 . The circuit of claim 22 further comprising a control circuit connected to said gate.
24 . The circuit of claim 1 wherein said control circuit is coupled between a first voltage potential and a second voltage potential.
25 . The circuit of claim 22 wherein said control circuit comprises at least one of a RC circuit, voltage detection circuit current detection circuit, short circuit and open circuit.